This application is in response to RFA 86-CA-10, National Collaborative Imaging Trails Project. We have organized a group of institutions to form the Radiologic Diagnostic Oncology Group (RDOG). The collaborative group will be designed to provide a means whereby efficacy studies on and diagnostic imaging tests can be instituted in a timely fashion and whereby data can be analyzed in a accurate manner. Under the auspices of an operations center and statistical and data management group, we will establish an ongoing mechanism to: optimize image quality across all participating sites; obtain consistent and complete data across participating sites; create an imaging library to allow derivative studies in subsequent years; and analyze imaging data for clinical effectiveness and potential algorithm development using appropriate analytic techniques. The techniques employed for analysis will be state-of-the-art involving receiver operating characteristic curve analysis; special care will be taken to ensure correction for a number of biases that might preclude accurate data analyses. The application addresses the staging of both lung and prostate cancer. The absolute value of plain radiographs, CT, and MRI in the staging of patients with non-small-cell bronchogenic carcinoma will be determined; the incremental value of MRI over CT will also be assessed. For staging prostate cancer the accuracy of MRI and transrectal sonography will be determined in both absolute and incremental ways.